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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: iridescent shark

Synonyms and Other Names: Pangasius hypophthalmus (Sauvage, 1878), Pangasius sutchi Fowler, 1937; tra, swai, striped catfish, sutchi catfish

Taxonomy: available through www.itis.gov

Identification: Pangasianodon hypophthalmus is similar in body shape to blue (Ictalurus furcatus) and channel catfish (I. punctatus), but can be generally distinguished by the number of pairs of barbels around the mouth: P. hypophthalmus has only two pairs of maxillary barbels (at the corner of the mouth), whereas Ictalurus spp. have four pairs of barbels including chin (below the mouth) and nasal (above the mouth) barbels.

Size: 130 cm SL.

Native Range: Southeast Asia; Mekong and Chao Phraya rivers and Maeklong basins (Van Zalinge et al. 2002). Introduced into additional river basins for aquaculture (Roberts and Vidthayanon 1991).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Inhabits main channels of large rivers, moving to floodplains and marshy areas during flooding in the rainy season. Omnivorous, primarily feeding on algae, zooplankton, crustaceans, and fishes. Large migratory spawner, capable of long distance movements (>300 km) upstream in major rivers in Southeast Asia to spawning areas in northeastern Cambodia (Vidthayanon and Hogan 2011; Van Zalinge et al. 2002).

Means of Introduction: Unknown. Likely aquarium release as it is common in the trade.

Status: Unknown; likely failed.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Shafland et al. (2008) report the capture of five "false Siamese shark" (identified as Platytropius siamensis), stating that it is a common aquarium fish. However, this species has not been observed in the wild since the mid-1970s and is currently classified as extinct (Ng 2011), and thus was likely not common in the aquarium trade in 1988. This is likely a case of misidentified individuals of Pangasiodon hypophthalmus, which is commonly found in the aquarium trade, and the report of Shafland et al. (2008) is included here.

Farmed widely as a food fish in Asia, and sold in the U.S. as swai. Wild stocks have generally declined since the 1980s due to overexploitation (Vidthayanon and Hogan 2011). A related species, Pangasius bocourti, is also used in aquaculture and is marketed as basa.

References: (click for full references)

Ng, H.H. 2011. Platytropius siamensis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. http://www.iucnredlist.org, visited on 28 February 2013.

Roberts, T.R. and C. Vidthayanon, 1991. Systematic revision of the Asian catfish family Pangasiidae, with biological observations and descriptions of three new species. Proceedings of the Academy of Natural Sciences of Philadelphia 143:97-144.

Shafland, P.L., K.B. Gestring, and M.S. Stanford. 2008. Florida's exotic freshwater fishes - 2007. Florida Scientist 71(3):220-245.

Van Zalinge, N., L. Sopha, N. Peng Bun, H. Kong, and J.Valbo-Jørgensen. 2002. Status of the Mekong Pangasianodon hypophthalmus resources, with special reference to the stock shared between Cambodia and Viet Nam. MRC Technical Paper No. 1, Mekong River Commission, Phnom Penh.

Vidthayanon, C., and Z. Hogan. 2011. Pangasianodon hypophthalmus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.1. http://www.iucnredlist.org, visited on 10 September 2012.

Other Resources:
FAO Fisheries Cultured Aquatic Species Information Programme

US Fish and Wildlife Service Ecological Risk Screening Summary for Pangasianodon hypophthalmus

Author: Neilson, M.E., Loftus, W.F., and Benson, A.

Peer Review Date: 2/28/2013

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.